Magnetic cloud models with bent and oblate cross-section boundaries

Autores
Démoulin, P.; Dasso, S.
Año de publicación
2009
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Context. Magnetic clouds (MCs) are formed by magnetic flux ropes that are ejected from the Sun as coronal mass ejections. These structures generally have low plasma beta and travel through the interplanetary medium interacting with the surrounding solar wind. Thus, the dynamical evolution of the internal magnetic structure of a MC is a consequence of both the conditions of its environment and of its own dynamical laws, which are mainly dominated by magnetic forces.Aims. With in-situ observations the magnetic field is only measured along the trajectory of the spacecraft across the MC. Therefore, a magnetic model is needed to reconstruct the magnetic configuration of the encountered MC. The main aim of the present work is to extend the widely used cylindrical model to arbitrary cross-section shapes.Methods. The flux rope boundary is parametrized to account for a broad range of shapes. Then, the internal structure of the flux rope is computed by expressing the magnetic field as a series of modes of a linear force-free field.Results. We analyze the magnetic field profile along straight cuts through the flux rope, in order to simulate the spacecraft crossing through a MC. We find that the magnetic field orientation is only weakly affected by the shape of the MC boundary. Therefore, the MC axis can approximately be found by the typical methods previously used (e.g., minimum variance). The boundary shape affects the magnetic field strength most. The measurement of how much the field strength peaks along the crossing provides an estimation of the aspect ratio of the flux-rope cross-section. The asymmetry of the field strength between the front and the back of the MC, after correcting for the time evolution (i.e., its aging during the observation of the MC), provides an estimation of the cross-section global bending. A flat or/and bent cross-section requires a large anisotropy of the total pressure imposed at the MC boundary by the surrounding medium.Conclusions. The new theoretical model developed here relaxes the cylindrical symmetry hypothesis. It is designed to estimate the cross-section shape of the flux rope using the in-situ data of one spacecraft. This allows a more accurate determination of the global quantities, such as magnetic fluxes and helicity. These quantities are especially important for both linking an observed MC to its solar source and for understanding the corresponding evolution. © 2009 ESO.
Fil:Dasso, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fuente
Astron. Astrophys. 2009;507(2):969-980
Materia
Interplanetary medium
Sun: coronal mass ejections (CMEs)
Sun: magnetic fields
Arbitrary cross section
Boundary shapes
Coronal mass ejection
Cylindrical models
Cylindrical symmetry
Dynamical evolution
Field strengths
Flux ropes
Global quantities
Helicities
In-situ data
In-situ observations
Internal structure
Interplanetary medium
Large anisotropy
Magnetic clouds
Magnetic configuration
Magnetic field orientations
Magnetic field profile
Magnetic field strengths
Magnetic flux ropes
Magnetic models
Minimum variance
Solar source
Sun: coronal mass ejection
Sun: magnetic field
Theoretical models
Time evolutions
Total pressure
Aspect ratio
Astrophysics
Boundary layer flow
Interplanetary spacecraft
Magnetic fields
Magnetic flux
Magnetic structure
Planetary surface analysis
Solar wind
Sun
Semiconductor counters
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by/2.5/ar
Repositorio
Biblioteca Digital (UBA-FCEN)
Institución
Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales
OAI Identificador
paperaa:paper_00046361_v507_n2_p969_Demoulin

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oai_identifier_str paperaa:paper_00046361_v507_n2_p969_Demoulin
network_acronym_str BDUBAFCEN
repository_id_str 1896
network_name_str Biblioteca Digital (UBA-FCEN)
spelling Magnetic cloud models with bent and oblate cross-section boundariesDémoulin, P.Dasso, S.Interplanetary mediumSun: coronal mass ejections (CMEs)Sun: magnetic fieldsArbitrary cross sectionBoundary shapesCoronal mass ejectionCylindrical modelsCylindrical symmetryDynamical evolutionField strengthsFlux ropesGlobal quantitiesHelicitiesIn-situ dataIn-situ observationsInternal structureInterplanetary mediumLarge anisotropyMagnetic cloudsMagnetic configurationMagnetic field orientationsMagnetic field profileMagnetic field strengthsMagnetic flux ropesMagnetic modelsMinimum varianceSolar sourceSun: coronal mass ejectionSun: magnetic fieldTheoretical modelsTime evolutionsTotal pressureAspect ratioAstrophysicsBoundary layer flowInterplanetary spacecraftMagnetic fieldsMagnetic fluxMagnetic structurePlanetary surface analysisSolar windSunSemiconductor countersContext. Magnetic clouds (MCs) are formed by magnetic flux ropes that are ejected from the Sun as coronal mass ejections. These structures generally have low plasma beta and travel through the interplanetary medium interacting with the surrounding solar wind. Thus, the dynamical evolution of the internal magnetic structure of a MC is a consequence of both the conditions of its environment and of its own dynamical laws, which are mainly dominated by magnetic forces.Aims. With in-situ observations the magnetic field is only measured along the trajectory of the spacecraft across the MC. Therefore, a magnetic model is needed to reconstruct the magnetic configuration of the encountered MC. The main aim of the present work is to extend the widely used cylindrical model to arbitrary cross-section shapes.Methods. The flux rope boundary is parametrized to account for a broad range of shapes. Then, the internal structure of the flux rope is computed by expressing the magnetic field as a series of modes of a linear force-free field.Results. We analyze the magnetic field profile along straight cuts through the flux rope, in order to simulate the spacecraft crossing through a MC. We find that the magnetic field orientation is only weakly affected by the shape of the MC boundary. Therefore, the MC axis can approximately be found by the typical methods previously used (e.g., minimum variance). The boundary shape affects the magnetic field strength most. The measurement of how much the field strength peaks along the crossing provides an estimation of the aspect ratio of the flux-rope cross-section. The asymmetry of the field strength between the front and the back of the MC, after correcting for the time evolution (i.e., its aging during the observation of the MC), provides an estimation of the cross-section global bending. A flat or/and bent cross-section requires a large anisotropy of the total pressure imposed at the MC boundary by the surrounding medium.Conclusions. The new theoretical model developed here relaxes the cylindrical symmetry hypothesis. It is designed to estimate the cross-section shape of the flux rope using the in-situ data of one spacecraft. This allows a more accurate determination of the global quantities, such as magnetic fluxes and helicity. These quantities are especially important for both linking an observed MC to its solar source and for understanding the corresponding evolution. © 2009 ESO.Fil:Dasso, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.2009info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfhttp://hdl.handle.net/20.500.12110/paper_00046361_v507_n2_p969_DemoulinAstron. Astrophys. 2009;507(2):969-980reponame:Biblioteca Digital (UBA-FCEN)instname:Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturalesinstacron:UBA-FCENenginfo:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by/2.5/ar2025-09-29T13:43:03Zpaperaa:paper_00046361_v507_n2_p969_DemoulinInstitucionalhttps://digital.bl.fcen.uba.ar/Universidad públicaNo correspondehttps://digital.bl.fcen.uba.ar/cgi-bin/oaiserver.cgiana@bl.fcen.uba.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:18962025-09-29 13:43:04.477Biblioteca Digital (UBA-FCEN) - Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturalesfalse
dc.title.none.fl_str_mv Magnetic cloud models with bent and oblate cross-section boundaries
title Magnetic cloud models with bent and oblate cross-section boundaries
spellingShingle Magnetic cloud models with bent and oblate cross-section boundaries
Démoulin, P.
Interplanetary medium
Sun: coronal mass ejections (CMEs)
Sun: magnetic fields
Arbitrary cross section
Boundary shapes
Coronal mass ejection
Cylindrical models
Cylindrical symmetry
Dynamical evolution
Field strengths
Flux ropes
Global quantities
Helicities
In-situ data
In-situ observations
Internal structure
Interplanetary medium
Large anisotropy
Magnetic clouds
Magnetic configuration
Magnetic field orientations
Magnetic field profile
Magnetic field strengths
Magnetic flux ropes
Magnetic models
Minimum variance
Solar source
Sun: coronal mass ejection
Sun: magnetic field
Theoretical models
Time evolutions
Total pressure
Aspect ratio
Astrophysics
Boundary layer flow
Interplanetary spacecraft
Magnetic fields
Magnetic flux
Magnetic structure
Planetary surface analysis
Solar wind
Sun
Semiconductor counters
title_short Magnetic cloud models with bent and oblate cross-section boundaries
title_full Magnetic cloud models with bent and oblate cross-section boundaries
title_fullStr Magnetic cloud models with bent and oblate cross-section boundaries
title_full_unstemmed Magnetic cloud models with bent and oblate cross-section boundaries
title_sort Magnetic cloud models with bent and oblate cross-section boundaries
dc.creator.none.fl_str_mv Démoulin, P.
Dasso, S.
author Démoulin, P.
author_facet Démoulin, P.
Dasso, S.
author_role author
author2 Dasso, S.
author2_role author
dc.subject.none.fl_str_mv Interplanetary medium
Sun: coronal mass ejections (CMEs)
Sun: magnetic fields
Arbitrary cross section
Boundary shapes
Coronal mass ejection
Cylindrical models
Cylindrical symmetry
Dynamical evolution
Field strengths
Flux ropes
Global quantities
Helicities
In-situ data
In-situ observations
Internal structure
Interplanetary medium
Large anisotropy
Magnetic clouds
Magnetic configuration
Magnetic field orientations
Magnetic field profile
Magnetic field strengths
Magnetic flux ropes
Magnetic models
Minimum variance
Solar source
Sun: coronal mass ejection
Sun: magnetic field
Theoretical models
Time evolutions
Total pressure
Aspect ratio
Astrophysics
Boundary layer flow
Interplanetary spacecraft
Magnetic fields
Magnetic flux
Magnetic structure
Planetary surface analysis
Solar wind
Sun
Semiconductor counters
topic Interplanetary medium
Sun: coronal mass ejections (CMEs)
Sun: magnetic fields
Arbitrary cross section
Boundary shapes
Coronal mass ejection
Cylindrical models
Cylindrical symmetry
Dynamical evolution
Field strengths
Flux ropes
Global quantities
Helicities
In-situ data
In-situ observations
Internal structure
Interplanetary medium
Large anisotropy
Magnetic clouds
Magnetic configuration
Magnetic field orientations
Magnetic field profile
Magnetic field strengths
Magnetic flux ropes
Magnetic models
Minimum variance
Solar source
Sun: coronal mass ejection
Sun: magnetic field
Theoretical models
Time evolutions
Total pressure
Aspect ratio
Astrophysics
Boundary layer flow
Interplanetary spacecraft
Magnetic fields
Magnetic flux
Magnetic structure
Planetary surface analysis
Solar wind
Sun
Semiconductor counters
dc.description.none.fl_txt_mv Context. Magnetic clouds (MCs) are formed by magnetic flux ropes that are ejected from the Sun as coronal mass ejections. These structures generally have low plasma beta and travel through the interplanetary medium interacting with the surrounding solar wind. Thus, the dynamical evolution of the internal magnetic structure of a MC is a consequence of both the conditions of its environment and of its own dynamical laws, which are mainly dominated by magnetic forces.Aims. With in-situ observations the magnetic field is only measured along the trajectory of the spacecraft across the MC. Therefore, a magnetic model is needed to reconstruct the magnetic configuration of the encountered MC. The main aim of the present work is to extend the widely used cylindrical model to arbitrary cross-section shapes.Methods. The flux rope boundary is parametrized to account for a broad range of shapes. Then, the internal structure of the flux rope is computed by expressing the magnetic field as a series of modes of a linear force-free field.Results. We analyze the magnetic field profile along straight cuts through the flux rope, in order to simulate the spacecraft crossing through a MC. We find that the magnetic field orientation is only weakly affected by the shape of the MC boundary. Therefore, the MC axis can approximately be found by the typical methods previously used (e.g., minimum variance). The boundary shape affects the magnetic field strength most. The measurement of how much the field strength peaks along the crossing provides an estimation of the aspect ratio of the flux-rope cross-section. The asymmetry of the field strength between the front and the back of the MC, after correcting for the time evolution (i.e., its aging during the observation of the MC), provides an estimation of the cross-section global bending. A flat or/and bent cross-section requires a large anisotropy of the total pressure imposed at the MC boundary by the surrounding medium.Conclusions. The new theoretical model developed here relaxes the cylindrical symmetry hypothesis. It is designed to estimate the cross-section shape of the flux rope using the in-situ data of one spacecraft. This allows a more accurate determination of the global quantities, such as magnetic fluxes and helicity. These quantities are especially important for both linking an observed MC to its solar source and for understanding the corresponding evolution. © 2009 ESO.
Fil:Dasso, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
description Context. Magnetic clouds (MCs) are formed by magnetic flux ropes that are ejected from the Sun as coronal mass ejections. These structures generally have low plasma beta and travel through the interplanetary medium interacting with the surrounding solar wind. Thus, the dynamical evolution of the internal magnetic structure of a MC is a consequence of both the conditions of its environment and of its own dynamical laws, which are mainly dominated by magnetic forces.Aims. With in-situ observations the magnetic field is only measured along the trajectory of the spacecraft across the MC. Therefore, a magnetic model is needed to reconstruct the magnetic configuration of the encountered MC. The main aim of the present work is to extend the widely used cylindrical model to arbitrary cross-section shapes.Methods. The flux rope boundary is parametrized to account for a broad range of shapes. Then, the internal structure of the flux rope is computed by expressing the magnetic field as a series of modes of a linear force-free field.Results. We analyze the magnetic field profile along straight cuts through the flux rope, in order to simulate the spacecraft crossing through a MC. We find that the magnetic field orientation is only weakly affected by the shape of the MC boundary. Therefore, the MC axis can approximately be found by the typical methods previously used (e.g., minimum variance). The boundary shape affects the magnetic field strength most. The measurement of how much the field strength peaks along the crossing provides an estimation of the aspect ratio of the flux-rope cross-section. The asymmetry of the field strength between the front and the back of the MC, after correcting for the time evolution (i.e., its aging during the observation of the MC), provides an estimation of the cross-section global bending. A flat or/and bent cross-section requires a large anisotropy of the total pressure imposed at the MC boundary by the surrounding medium.Conclusions. The new theoretical model developed here relaxes the cylindrical symmetry hypothesis. It is designed to estimate the cross-section shape of the flux rope using the in-situ data of one spacecraft. This allows a more accurate determination of the global quantities, such as magnetic fluxes and helicity. These quantities are especially important for both linking an observed MC to its solar source and for understanding the corresponding evolution. © 2009 ESO.
publishDate 2009
dc.date.none.fl_str_mv 2009
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/20.500.12110/paper_00046361_v507_n2_p969_Demoulin
url http://hdl.handle.net/20.500.12110/paper_00046361_v507_n2_p969_Demoulin
dc.language.none.fl_str_mv eng
language eng
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/2.5/ar
eu_rights_str_mv openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by/2.5/ar
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv Astron. Astrophys. 2009;507(2):969-980
reponame:Biblioteca Digital (UBA-FCEN)
instname:Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales
instacron:UBA-FCEN
reponame_str Biblioteca Digital (UBA-FCEN)
collection Biblioteca Digital (UBA-FCEN)
instname_str Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales
instacron_str UBA-FCEN
institution UBA-FCEN
repository.name.fl_str_mv Biblioteca Digital (UBA-FCEN) - Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales
repository.mail.fl_str_mv ana@bl.fcen.uba.ar
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